Witnesses told police Patrick hit a safety fence and landed on the roof of another stall.

Police and workplace health and safety officers are investigating whether the boy was too young or too small for the ride, or if the safety equipment failed.

Carnival Land Amusements, which rents out the rides to schools, outlines on its website that the height requirements for the ride are 130 centimetres for unaccompanied children and 110 centimetres for those with an adult.

Attorney-General Jarrod Bleijie confirmed his department would be overseeing the continuing Workplace Health and Safety investigation.